The present disclosure relates generally to the field of adjustable seat assemblies. More particularly, the present disclosure relates to the field of seat adjuster systems for use with adjustable vehicle assemblies including a seat.
Vehicle seat assemblies commonly include a seat (having a seat bottom and a seat back) and a seat adjuster system that enables the position of the seat within the vehicle to be adjusted. Seat adjuster systems are used with seats of the vehicle to provide selective horizontal fore and aft movement of the seat, vertical movement of the seat, and/or pivotal movement of the seat back. The ability to adjust the position of the seat is desirable to enable vehicle seat occupants of various sizes to be seated comfortably and safely within the motor vehicle.
Seat adjuster systems commonly include a support frame which supports the seat bottom on a track system. To provide for horizontal movement, typically in a fore and aft vehicle direction, the track system commonly includes at least two track assemblies or arrangements that are located on each side of the seat. Each track arrangement generally includes two or more tracks that move relative to one another and a device or assembly that controls the ability of the tracks to move relative to one another. Some seat adjuster systems utilize a powered drive mechanism (typically an electric motor) in conjunction with a system of gears and other components to control the relative positions of the individual tracks of each track arrangement. For example, it is known to use a threaded drive screw in combination with one or more gears positioned between an output of the powered drive mechanism and the drive screw. To move a seat coupled to such a track system to a new position, the occupant simply activates the powered drive mechanism, which through a series of additional components (e.g., a drive screw, gear configuration, etc.), causes the individual tracks to move relative to one another.
Similar track systems and drive mechanisms are generally provided for vertical (up and down) adjustment of the seat support frame and, in a seat adjuster system having a seat recliner adjustment mechanism, for angularly adjusting the position of the seat back with respect to the seat bottom. The vertical drive mechanism may also include separate front, rear, and/or side edge seat adjustment drive mechanisms for selectively tilting the front, rear, and/or side edges of the seat bottom independent of each other as well as to raise and lower the entire vehicle seat or, in some applications, only the seat bottom or cushion.
Seat assemblies (and thus seat adjuster systems) are known to be susceptible to loads of greater magnitude than loads experienced during normal use (i.e., those loads typically realized when seat occupants are seated in the seat assemblies). For example, loads of greater magnitude may be realized by the seat assemblies when a vehicle experiences a frontal or rear impact (e.g., collision, etc.). Such loads may cause one or more components of the seat adjuster system to fail.
For example, when a vehicle experiences a rear impact, an increased load is transferred from a seat occupant to the seat back. Referring to FIG. 7, a common load path has the load transferring from the seat back to the track system, from the track system to a threaded lead screw of a vertical lift system, from the lead screw to a gear and/or drive nut (commonly formed of plastic) engaging the lead screw, and subsequently from the drive nut to a housing and/or bracket (at least one of which is commonly formed of metal) used to mount to the vertical lift system to a support structure (e.g., the track system, etc.). A flat thrust washer is provided between the drive nut and the housing. The positioning of a gear and/or drive nut formed of plastic in the load path along with adjacent components commonly formed of metal, may cause the gear and/or drive nut to fail (e.g., crack, peel, lose position on the drive screw, etc.) if the vehicle experiences a sufficient impact.
Accordingly, it would be advantageous to provide a seat adjuster system that cushions or otherwise protects a gear and/or drive nut within the seat adjuster system from an axial load. It would be also advantageous to provide a seat adjuster system that is capable of transferring an axial load realized by a gear and/or drive nut engaging a threaded drive screw to an adjacent support structure in a way that reduces the likelihood that the gear and/or drive nut might fail. It would also be advantageous to provide a seat adjuster system that reduces the likelihood that a plastic gear and/or drive nut within the seat adjuster system will fail during an impact. It would also be advantageous to provide a seat adjuster system having a vertical lift drive system utilizing a plastic gear and/or drive nut that is better protected from an axial force. To provide a seat adjuster system having one or more of these, or any other advantages realized from the present disclosure, would be a significant advancement.